An interline-transfer CCD imager with floating photodiodes

An interline-transfer CCD imager with "floating photodiodes" is described and demonstrated. The new cell design combines the transfer gate and a gate electrode of the vertical shift register into a single gate, eliminating the first level polysilicon layer, It consequently requires two levels of polysilicon instead of three, and results in a simple structure. The floating photodiodes fabricated by ion implantation provide high sensitivity even at short wavelengths. A quantum efficiency of 20% at 400 nm light has been obtained from the 488 × 385-element imager fabricated using a two-level polysilicon gate technology. This cell design offers significant advantages in high performance and potentially high yield.